far too young, krystle campbell. martha: the boston bombings have raised concerns that the lines are blurring between u.s. and foreign terror plots. this as investigators look into whether tamerlan tsarnaev may have been trained overseas last year in chechnya. it's something that experts say is happening more and more. you've got 60 plots at least that they know of that have involved home-grown terrorists since 9/11. fortunately most of them have been thwarted but not this time. we were not so lucky. i am joined by a former special assistance to the president for homeland security and associate vice president at george washington university and director of the homeland security policy institute. frank, well cox. good to have you here. >> thank you, martha, thanks. martha: you've seen a lot in your career. what does your gut tell you about whether or not they were part of anything larger or whether or not they had anything else planned. >> you know the threat today comes in various shapes, sizes and forms ranging from